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Fencer Vulns
medium 6.3

CVE-2026-86805 json

AT_SECURE programs may load attacker-controlled code via $ORIGIN

published 2026-09-22 47 d ago modified 2026-09-23 47 d ago also EUVD-2026-84540

cvss
6.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 0%
public exploits
0
none known

Summary

A time-of-check to time-of-use (TOCTOU) race condition in the dynamic loader (ld.so) of the GNU C Library (glibc) versions 2.14 through 2.44 allows a local attacker to escalate privileges. When expanding $ORIGIN in DT_RPATH for setuid/setgid (AT_SECURE) programs, glibc validates the lexically normalized search path against the trusted directories but then opens the raw, un-normalized path. On systems where the Linux fs.protected_hardlinks sysctl is disabled, a local attacker who hard-links such a program into an attacker-controlled directory and wins a race to replace an intermediate path component with a symbolic link can direct the loader outside the trusted directory, causing it to load an attacker-controlled shared object and execute arbitrary code with the elevated privileges of the program.

Exploitation requires an installed setuid or setgid binary whose DT_RPATH uses $ORIGIN followed by ".." traversal that normalizes into a trusted directory, and the ability to hard-link that binary and win the race by swapping a path component for a symbolic link. Major Linux-based OS distributions ship with fs.protected_hardlinks enabled by default and mitigate the vulnerability.

Patch / fix

  • The GNU C Library glibc 2.45
  • glibc Debian 14 2.43-7

debian advisories DEBIAN-CVE-2026-86805

  • glibc hummingbird 1 2.43-8.7.hum1
  • libnsl hummingbird 1 2.43-8.7.hum1
  • nss_db hummingbird 1 2.43-8.7.hum1
  • glibc32 hummingbird 1 2.43-8.7.hum1
  • nss_hesiod hummingbird 1 2.43-8.7.hum1
  • glibc-utils hummingbird 1 2.43-8.7.hum1
  • glibc-common hummingbird 1 2.43-8.7.hum1
  • glibc-benchtests hummingbird 1 2.43-8.7.hum1

red hat advisories RHSA-2026:72503

  • glibc Linux Micro 6.1 2.38-slfo.1.1_11.1
  • glibc Linux Micro 6.0 2.38-159998.1.1
  • glibc SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Development Tools 15 SP7 +1 more 2.38-150600.14.61.1
  • glibc SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +8 more 2.31-150300.109.1
  • glibc SLES 16.0, Linux Micro Extras 6.2, Linux Micro 6.2 +1 more 2.40-160000.7.1
  • glibc SLES 11 SP4 LTSS EXTREME CORE 2.11.3-17.110.58.1
  • glibc SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 2.22-114.55.1

suse advisories SUSE-SU-2026:24281-1SUSE-SU-2026:24326-1SUSE-SU-2026:4669-1SUSE-SU-2026:4656-1SUSE-SU-2026:4654-1SUSE-SU-2026:4591-1

  • glibc openSUSE Tumbleweed 2.44-3.1
  • glibc openSUSE Leap 16.0 2.40-160000.7.1
  • glibc-cross-s390x-src openSUSE Leap 16.0 2.40-160000.7.1
  • glibc-cross-aarch64-src openSUSE Leap 16.0 2.40-160000.7.1
  • glibc-cross-ppc64le-src openSUSE Leap 16.0 2.40-160000.7.1
  • glibc-cross-riscv64-src openSUSE Leap 16.0 2.40-160000.7.1

opensuse advisories openSUSE-SU-2026:12072-1openSUSE-SU-2026:21968-1

  • glibc AlmaLinux 9 2.34-284.el9_8.4
  • nscd AlmaLinux 9 2.34-284.el9_8.4
  • libnsl AlmaLinux 9 2.34-284.el9_8.4
  • glibc-utils AlmaLinux 9 2.34-284.el9_8.4
  • glibc-gconv-extra AlmaLinux 9 2.34-284.el9_8.4
  • glibc-all-langpacks AlmaLinux 9 2.34-284.el9_8.4
  • glibc-locale-source AlmaLinux 9 2.34-284.el9_8.4
  • glibc-minimal-langpack AlmaLinux 9 2.34-284.el9_8.4

almalinux advisories ALSA-2026:95618

  • glibc Rocky Linux 9 2.34-284.el9_8.4

rocky linux advisories RLSA-2026:95618

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-86805 updated cvss 7.0

glibc: glibc: Privilege escalation and arbitrary code execution via TOCTOU race condition in dynamic loader

  • Red Hat Enterprise Linux 7 nscd, glibc, glibc-utils, glibc-common Red Hat Enterprise Linux 10 glibc Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: no fix available
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-core-bff-rhel9, rhoai/odh-dashboard-rhel9, rhoai/odh-mod-arch-maas-rhel9, rhoai/odh-mod-arch-automl-rhel9, rhoai/odh-mod-arch-gen-ai-rhel9, rhoai/odh-mod-arch-mlflow-rhel9, +6 more
    under investigation
  • Red Hat Enterprise Linux AppStream (v. 8) glibc-utils 2.28-251.el8_10.53, compat-libpthread-nonshared 2.28-251.el8_10.53
    fixed: vendor fix RHSA-2026:96087
  • Red Hat Enterprise Linux AppStream (v. 9) glibc-utils 2.34-284.el9_8.4, glibc-locale-source 2.34-284.el9_8.4
    fixed: vendor fix RHSA-2026:95618
  • Red Hat Enterprise Linux BaseOS (v. 8) nscd 2.28-251.el8_10.53, glibc 2.28-251.el8_10.53, libnsl 2.28-251.el8_10.53, nss_db 2.28-251.el8_10.53, glibc-common 2.28-251.el8_10.53, glibc-gconv-extra 2.28-251.el8_10.53, +3 more
    fixed: vendor fix RHSA-2026:96087
  • Red Hat Enterprise Linux BaseOS (v. 9) nscd 2.34-284.el9_8.4, glibc 2.34-284.el9_8.4, libnsl 2.34-284.el9_8.4, glibc-common 2.34-284.el9_8.4, glibc-gconv-extra 2.34-284.el9_8.4, glibc-all-langpacks 2.34-284.el9_8.4, +1 more Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) nss_db 2.34-284.el9_8.4, nss_hesiod 2.34-284.el9_8.4, glibc-benchtests 2.34-284.el9_8.4
    fixed: vendor fix RHSA-2026:95618
  • Red Hat Enterprise Linux CRB (v. 8) nss_hesiod 2.28-251.el8_10.53, glibc-benchtests 2.28-251.el8_10.53
    fixed: vendor fix RHSA-2026:96087
  • Red Hat Hardened Images glibc 2.43-8.7.hum1, libnsl 2.43-8.7.hum1, nss_db 2.43-8.7.hum1, glibc32 2.43-8.7.hum1, nss_hesiod 2.43-8.7.hum1, glibc-utils 2.43-8.7.hum1, +9 more
    fixed: vendor fix RHSA-2026:72503
show 1 more
  • Red Hat Enterprise Linux 6 nscd, glibc, glibc-utils, compat-glibc, glibc-common Red Hat Enterprise Linux 7 compat-glibc Red Hat OpenShift AI (RHOAI) rhoai/odh-mlflow-rhel9, rhoai/odh-kube-rbac-proxy-rhel9, rhoai/odh-maas-controller-rhel9, rhoai/odh-mlflow-operator-rhel9, rhoai/odh-model-controller-rhel9, rhoai/odh-ogx-k8s-operator-rhel9, +14 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
48 d ago

Exploit prediction

0.10% chance of exploitation in the next 30 days, higher than 0% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.3 CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L

Affected products

  • The GNU C Library glibc

Classification

Weakness
  • CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.